Expansion joint

ABSTRACT

An expandable track section particularly useful for joining sections of an electrical signal or power track. The expandable section comprises a track portion with numerous lateral slots on either side forming a zig-zag member.

United States Patent Janzow et al.

EXPANSION JOINT Inventors: Lester G. Janzow, 6128 Flight Ave.,

Los Angeles, Calif. 90056; Ronald D. Lipke, 5037 Muriotta, Sherman Oaks, Calif. 91403 Filed: Oct. 12, 1971 Appl. No.: 188,500

Related U.S. Application Data Division of Ser. No. 767,297, Oct. 14, 1968, Pat. No. 3,637,957.

U.S. Cl. 238/228, 238/151 Int. Cl E01b 11/02 Field of Search 238/151, 218, 219, 220, 238/221, 230, 232, 234, 175, 122, 127; 191/29 References Cited UNITED STATES PATENTS 6/1892 Moxham 238/228 [4 1 June 11, 1974 477,673 6/1892 Moxham 238/228 477,675 6/1892 238/228 1,080,481 12/1913 238/225 1,257,945 2/1918 238/175 1,798,004 3/1931 Speranza 238/225 3,528,608 9/1970 ,Dashew et a1. 238/151 Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerRichard A. Bertsch Attorney, Agent, or Firm.lohn S. Bell [5 7] ABSTRACT An expandable track section particularly useful for joining sections of an electrical signal or power track. The expandable section comprises a track portion with numerous lateral slots on either side forming a zig-zag member.

1 Claim, 7 Drawing Figures Pmmmm 1 1 m4 sum 1 or 2 lOA lqok

EXPANSION JOINT CROSS REFERENCE TO RELATED APPLICA- TION This application is a division of US. Pat. application Ser. No. 767,297 filed Oct. 14, 1968, now US. Pat. No. 3,637,957.

BACKGROUND'OF THE INVENTION l. Field of the Invention This invention relates to tracks forengaging elements of a vehicle.

2. Description of the Prior Art Electrically powered vehicles often receive currents from power tracks which extend along the vehicle route. The power tracks are engaged by shoes on the vehicle which slide along the track face. Track systems generally include numerous expansion joints which take up expansion and contraction caused by variations in ambient temperature. It is desirable that the joints provide a smooth path for the shoe, to prevent wear on it or the track, and that there be no gaps or areas of high resistance where arcing and hot spots may develop. One such joint is disclosed in U.S. Pat. No. 3,528,608 by Dashew and Janzow, which is assigned to the assignee of the present application.

OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide a track expansion joint which supplies a very smooth path for vehicle elements.

Another object is to provide a current-carrying expansion joint which minimizes hot spots and arcing.

In accordance with the present invention, track expansion apparatus is provided which establishes a smooth path for vehicle elements. In one embodiment of the invention, the joint comprises a section of track with alternate lateral slots which form it into a zig-zag shape. The joint section is placed in series with long lengths of ordinary track to take up expansion and contraction in them. A bracing bar is inserted into the joint section to support it against sagging and twisting. The bracing bar is fixed to one end of the joint section and can slide relative to the rest of it.

The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawmgsv DESCRIPTION OF THE DRAWINGS FIG. 5 is a simplified diagram showing the manner of manufacturing the expansion joint of FIG. 1;

FIG. 6 is a perspective exploded view of an expansion joint constructed in accordance with another embodiment of the invention; and

FIG. 7 is a sectional end view of the joint of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 4 illustrate an expansion joint section 10 for connection in series with two main power track sections 12 and 14. Theface 16 of the track is engaged by a shoe 18 of a vehicle. The vehicle is propelled by an electric motor, and the shoe carries energizing currents from the track to the motor. The joint section 10 can expand and contract considerably in length to take up contractions and expansions, respectively, in the main track sections .12 and 14.

Both the main and joint tracks are of C cross-section, with a base 20, flanges 22 and 24 extending rearwardly from the base, and lips 26 and 28 extending toward each other from the ends of the flanges. A multiplicity of lateral cuts or slotsare formed in the joint section, to leave a member of zig-zag form. Slot 30 extends laterally through the upper flange 22 and lip 26, and continues laterally through the base 20 down to a position near the lower flange 24. The slots 32 and 34 on either side of slot 30 extend in a complementary manner through the lower flange and through the base up to a position near the upper flange. Numerous other slots are spaced along the length of the track section, with alternate slots cut in a complementary manner.

When the main track sections 12 and 14 are subjected to low temperatures and they contract, the joint section 10 is subjected to tension. It expands to the configuration shown in FIG. 4, wherein the slots open and the small portions of track between the slots move away from each other.

Because of the series of slots in the joint section, it is weakened and could sag. Also, if not reinforced it could be deflected by the force of the shoe 18, which may press with a force on the order of 30 pounds for a 2 inch wide track. In order to fix the position of the joint section, an insert or bracing bar 36 is provided. The bar has one end portion 38 fixed to both the main track section 12 and the end 40 of the joint section. The attachment is accomplished by a connecting plate 42 and four bolts 44 which extend through holes in the plate and engage threaded holes in the bracing bar. The rest of the bracing bar, including the opposite end 46, is free to slide within the joint section.

The opposite end portions 40 and 50 of the joint section are free of slots to strengthen them. These ends 40 and 50 are held to the main track sections by the connecting plate 42 and by another connecting plate 52 and a small additional insert bar 54. As the joint section expands or contracts, the bracing bar slides relative to it, providing support against sagging and against deflection away from the shoe, and also preventing twisting. To this end, the bracing bar 36 has a cross-section closely mated to the free area within the C-shaped track, so it is adjacent to or engages the inner surface of the base and flanges of the track.

Even in a fully expanded configuration such as that shown in FIG. 4, only short gaps exist. This promotes smooth travel over the track. The area over which the shoe contacts the track surface 16 is decreased only a small percentage during passage over the expanded joint section. Thus, a low resistance contact can be maintained. For signal-carrying tracks, this prevents large loss of signal power. For power tracks, this prevents arcing and the development of hot spots.

The tracks are preferably constructed of a material of high conductivity, such as aluminum. The slots can be formed by saws or other well known apparatus. The slots preferably do not extend into or even nick the opposite flange, e. g., slot 30 preferably does not reach the lower flange 24. This is to reduce the chance of fatigue failure at the ends of the slots where high stresses may be produced during joint expansion. The large depth E of the flanges enables them to resist the high stresses. Fatigue failure may also be resisted by enlarging the ends of the slots, as by drilling holes at the ends.

In the manufacture of the joint section, it is desirable to round the walls of each slot to assure smooth shoe travel. This can be accomplished in the manner shown in FIG. 5, by bending the joint section so the front surface which contacts the vehicle shoe it convexly curved as shown at 16A. A rotating wire brush 60 is then passed along the surface. The brush removes burrs and slightly rounds the walls of the slot at the front joint surface. Tracks of aluminum constructed in accordance with the foregoing description, of 3 /2 foot length with cuts spaced at /2 inch intervals, have been found to readily expand 6 inches without damage.

FIG. 6 illustrates another form of expansion joint apparatus, which is suitable for use with the main track of C cross-section described above, to tie two track sections 66 and 68 together. In the joint apparatus of FIG. 6, a joint member 70 is provided which is of the same form as the bracing bar 36 described above, except that it has three elongated fingers 72, 74 and 76 that extend along the length of the bar. Three slots 78, 80 and 82 are formed in the end of the track section 66, at the face or base thereof, for receiving the three fingers of the joint member. One end portion 86 of the joint member, which is devoid of the fingers, can be received in the other track section 68, and is held therein by bolts that extend through a connecting plate 88 and through threaded holes and 92 in the joint member.

When the joint of FIG. 6 is assembled, the fingers 72 through 76 are held in the slots 78 through 82, and slide longitudinally therein to take up expansion and contraction in the track sections 66 and 68. The joint section 70, by fitting into the track section 66, holds the main track sections in alignment.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. Expansion joint apparatus for vehicle engaging tracks comprising:

first and second track sections for connection in series, each track section having a C cross section with a front surface for engaging an element of said vehicle, each track section further having a plurality of longitudinally extending slots in its front surface portion at only one end;

a joint member to hold said track sections in alignment having a cross section closely mated to the free area within the C cross section of said track sections, said joint section having a first end portion fixedly disposed within the C cross section of said first track at the end of said track section opposite said one end having said slots and a second end portion slidably disposed within the C cross section of said second track section at said one end having said slots, said second end section of said joint member having a plurality of longitudinal fingers, slidably engaged in said slots to hold said track sections in alignment. 

1. Expansion joint apparatus for vehicle engaging tracks comprising: first and second track sections for connection in series, each track section having a C cross section with a front surface for engaging an element of said vehicle, each track section further having a plurality of longitudinally extending slots in its front surface portion at only one end; a joint member to hold said track sections in alignment having a cross section closely mated to the free area within the C cross section of said track sections, said joint section having a first end portion fixedly disposed within the C cross section of said first track at the end of said track section opposite said one end having said slots and a second end portion slidably disposed within the C cross section of said second track section at said one end having said slots, said second end section of said joint member having a plurality of longitudinal fingers, slidably engaged in said slots to hold said track sections in alignment. 